Okies update on this....
5700km from Tassie to Coober pedy, Oonaddatta track, Lake Ayre, Broken Hill, Ballarat and home Towing a 1370kg Camper Trailer plus loaded with spare fuel, water, tools etc.....The result is NO limp modes so im sure this fix has worked.
But I would advise replacing the Intercooler pipes (inlet / outlet) with aftermarket alloy/SS ones as I blew my Inlet pipe pretty conclusively (3 inch gash), appears the factory ones just aren't up to the task of dealing with the boost upgrades etc..
Power was good, the truck held nicely on cruise control in 5th, I tend to drop to 4th if 5th starts to slip in speed but never once had to drop to 3rd for any hill I met.
The tally after trip was 2 roo strikes (one took out my rear drivers quarter panel and all the plastics from the tub / wheel arch) other strike was on bull bar (no damage), one badly blown Inter cooler hose, 1 broken windscreen (truck delivered a nice fat stone center of mass)..
All up I cant fault the overall tune and exhaust although there is a low end drone in the exhaust, nothing that irritates just a new note when cruising the long flat highways..Fuel economy was over all 13.5 lt / 100k for the trip (2000 ish K was spent at or below 80 km/h given corrugations, dire gravel etc)
Pat.